Vehicles, including passenger automobiles, are engineered to perform under certain anticipated operating conditions and constraints, and in particular within maximum loading capacities defined relative to carrying weight and towing weight parameters. Generally vehicle manufacturers determine and provide individual vehicle rating specifications to owners and operators that indicate how much weight a vehicle can safely support and tow. The total recommended amount of weight that can be safely supported by a vehicle is known as the vehicle's gross vehicle weight rating (GVWR), which includes the weight of the vehicle itself (also known as the “curb weight”), fuel and other fluids, passengers, and all cargo. The Maximum Gross Trailer Weight (MGTW) is the recommended maximum weight that a particular vehicle can safely haul when attached to a vehicle trailer hitch. It is intended that owner/operators apply these ratings in loading and operating their vehicles.
However, a given vehicle may be offered with a plurality of option choices, so similar base-model vehicles may have divergent curb weights dependent upon the specific options chosen (or omitted) at or after manufacture, and intervening parties may install additional after-market options that increase the curb weight and proportionately reduce the actual load carrying capacity of the vehicle. Accordingly, actual vehicle curb weights are not generally provided to end user owner/operators by manufacturers or dealers but must be determined on a vehicle-by-vehicle basis by each owner or operator. Moreover, cargo and passenger weights may be unknown, and cargo and passenger loading may vary widely from trip to trip or during portions of a trip as passengers enter and leave a vehicle, or cargo portions are removed or added. If the vehicle is also used in towing applications, hitching a trailer or other towed article to a rear bumper hitch also adds a tongue weight load to vehicle through the hitch, for which cargo and passenger weight carrying capacity must be reduced accordingly; and moreover, the tongue weight actually applied may be unknown or undeterminable. Thus even if a vehicle operator has determined an actual load capacity, he may not be able to accurately or consistently apply the determined capacity in passenger and cargo loading.